I just remembered some old journal article about mold that mentioned studies in factories. I went to OSHA and found this. I think some of the oldest studies on mold exposure rose out of unhealthy work places. Osha has links, full of links on it.

Oops,, as a new member, Mayo won't let me post links - it won't let me post the link to the osha page. So let me do it this way. Osha (dot) gov (forward slash) mold. You can also find the page by googling two words: OSHA mold